Method of treating petroleum residues



1936. c. w. ANDREWS ET AL Q 2,051,462

METHOD OF TREATING PETROLEUM RESIDUES Filed Dec. 2'7, 1932 ZZZ/6735M Charles Wdrzdrewa flay 5 Petereem Patented Aug. 18 1936 UNITED STATES PATENT OFFICE RESID Charles W. Andrews, Chicago,

Petersen,

111., and Roy 8.

San Antonio, Tex., assignors to Brassert-Tidewater Development Corporation, Chicago, 111., a corporation of Delaware Application December 27,

1 Claim.

This invention relates to a new and improved method for treating petroleum residues, and more particularly to a method of vacuum flashing such residues and thereafter reducing the viscosity and pour point of the gas oil produced by the flashing operation.

It is well known in the art that many residues running from ten to fifteen A. P. I. gravity can be better utilized if they are separated into a gas oil and pitch, which may be accomplished by any one of several well known methods. This separation, however, has the very serious objection that if sufficient gas oil is removed to make the separation preferable, the pitch remaining is very dimcult to treat in any usual manner. The pitch is of a nature such that ordinarily its only use is that of fuel around the plant. In some cases it may be used for asphalts, and only in very rare cases is it hard enough to be used under boilers as a powdered fuel. Another objection to separation by usual processes lies in the fact that the overhead gas oil unless given a further cracking treatment, has such a high cold test that its commercial value is quite low.

It is an object of the present invention to provide a method of treatment of residues from cracking coils, topping of crudes or the like which comprises separating the residues into a gas oil of low cold test and into a coke of high commercial value.

It is a further object of the invention to provide a method of treating residues of the character described in which the viscosity of the overhead from a flashing treatment of such residues is'materially lowered.

It is also an object to provide a method in which the pitch resulting from a flashing of such cracked coll residues is reduced to a merchantable coke.

It is a further object to combine the treatment of the overhead and pitch resulting from flashing the cracking coil residues so that additional volatiles removed from the pitch may be jointly treated with volatiles derived from the overhead.

It is also an object to provide a method whereby the overhead from the vacuum flashing oi. the cracking coil residues may be heated in a viscosity breaker of. usual pipe still design, and the heat absorbed by said overhead utilized in the further treatment of the pitch from the flashing operation.

Other and further objects will appear as the description proceeds.

We have shown in the single figure which constitutes the attached drawing, a diagrammatic lssa'serm No. 648.998

layout of apparatus adapted for carrying out our invention shown in elevation with parts in section.

In the drawing, the feed line I I is shown leading to the vacuum flash tower l2. The overhead from the flash tower passes off through the line I 3 to the condenser l4. From condenser l4 the overhead products comprising gases and condensible vapors pass through line I 5 to the accumulator IS. The accumulator I 6 is provided 10 with the overhead vent line l1 which is connected into the upper portion of the bubble tower l8. The accumulator I 6 is also connected by line I 9 to pump 20 which discharges through line 2| to the pipe still or viscosity breaker 22. This viscosity breaker is preferably a standard type pipe still heater suitable for temperatures of 1000" F. in the outgoing stream and such pressures as may be desirable based on the type 01' charging stock. The top of the pipe still discharges through line 23 which divides, line 24 leading through valve 25 to the line 26. Line 23 is also connected through valve 21 with line 28 which leads into the lower portion of the bubble tower l8. 2 The residue from the flash tower 12 is carried of! through line '29 by means of pump 38, which delivers into line 3|. The line 3| joins line 24 at line 26. Line 26 is provided with the discharge lines 32 and 33 leading into the coking chambers 34 and 35. These chambers 34 and 35 are provided with flat floors which may be externally heated from below by means of fines 36 and 31.

The overhead vapors and gases from the coking chambers 34 and 35 are carried oil. through 35 passages 38 and 33 which join in passage 48 leading to an intermediate portion of the bubble tower l8. The overhead from bubble tower. l8 leads through line 4| to condensers 42 and 43 and thence through line 44 to the gas separator 45. From the separator 45 gas is carried off through line 46. The distillate from the gas separator passes of! through line 41 to pump 48. Pump 48 discharges through line 49 to line 58 controlled by valve'5l. Line 58 may lead to any 45 suitable means for utilizing or storing the distillate. Line 49 also discharges into line 52 controlled by valve 53. This line 52 leads into the top of the bubble tower at point 54, the distillate being used in the contact apparatus in the bubble tower. The gas oil from the bottom of bubble tower l8 passes oil! through line 55 and through cooler 56 to line 5'! which may lead to any suitable gas oil storing or using apparatus (not shown).

By the use of the apparatus layout shown in the drawing, we propose to obviate the disadvantages which are present in a separation of cracking coil residues into gas oil and pitch by any of the usual methods. Our method comprises as an initial step, the vacuum flashing of the hot residuum from a cracking unit in a conventional vacuum flash tower, such as shown at [2 in the drawing. This hot residuum from the cracking unit would normally be introduced into the vacuum flashtower at atemperature from 750 to. 850 F. The overhead vapors from the flash tower are condensed in condenser I4 and from the accumulator Hi the overhead condenser is forced by pump 20 through the coils in the viscosity breaker or pipe still 22, which may be of usual design. This still is capable of raising the temperature of this overhead condensate to approximately 1000 F. This operation may be conducted either in a vapor phase or in a liquid phase or in a combined operation, as may be desired.

In some cases it may be desirable to use a steam jet to develop the vacuum in the flash tower and at the same time the jet will force the vapors directly into the pipe still without the necessity of condensing and pumping.

The pitch collected in the bottom of the flash tower I2 is pumped by the pump 30 through line 3| to the junction with line 26, where it meets all or part of the overhead coming from the still or viscosity breaker 22. The mixture of overhead and pitch is discharged into the coking chambers 34 and35 and the overhead from the coking chambers is passed through a suitable vapor line 40 to the bubble tower l8. The coking chambers 34 and 35 a are preferably operated at substantially atm'ospheric pressures. The bottoms from the bubble tower l8, which will include heavier fractions of the overhead from the coking chamber and which will be a relatively small percentage of the total input, can either be returned to the flash tower l2 or returned to the regular cracking unit if desired. The overhead from the bubble tower after condensation is separated into gas and distillate or gas oil as may be desired. Any excess amount of material passing through the viscosity breaker not needed for heating the pitch and for the treatment in coke ovens, may be passed dlrectly through line 28 to the bubble tower. This material would then be treated in the bubble tower in the same manner as the overhead vapors coming from the coking chambers 34 and 35.

The coking chambers may be of the type which are externally heated and this external heat may be used it sufllcient heat for the coking operation is not derived from the hot overhead coming from the viscosity breaker. It may be desired to apply heat externally to the floors of the coking chambers in order to produce a harder, denser coke having a greater commercial value.

By our improved method the gas oil flashed in the flash tower which would otherwise have a relatively high pour point, may be reduced to whatever pour point, such for example as zero, may be necessary for commercial requirements. The bottom's from the bubble tower may in some instances be returned direct to the vacuum unit if this proves desirable. When this method of operation is used, the entire products of the operation will be concentrated in the separator connected with the bubble tower and will be gas and gas oil carrying varying proportions of distillate, depending on the amount of cracking which has been taking place. The solid residues of the process will be removed from the coking chambers as a merchantable coke. These coking chambers may be provided with doors at their ends so that the layer of coke formed may be periodically removed by mechanical pushers.

The term cracking coil residues used herein is intended to cover petroleum residues from cracking coils or any other sources such as the reduction of crude oils and in some instances preheated heavy crude oils. While we have de-. scribed vacuum flashing we do not confine ourselves to this method of flashing, as similar results may be obtained by using steam.

While we have shown and described one preferred method of carrying out our improved process for the treatment of cracking coil residues or the like, it will be understood that this is illustrative only, as it is capable of variation and change to meet differing conditions and requirements and we contemplate such changes and modifications as come within the spirit and scope of the appended claim.

We claim:

The method of treating petroleum residues, which comprises flashing said residues, condensing overhead vapors from the flashing operation,

' heating said condensed overhead to approximately 1000 F., mixing heated overhead and residue from the flashing operation. introducing said mixture directly into a coking chamber maintained at substantially atmospheric pressure, heating said chamber externally from below, drawing of! the overhead vapors and gases from said coking chamber, Iractionating said overhead and returning heavier fractions to the flashing operation, and coking the residue in said chamber as a solid layer of hard, dense coke.

. CHARLES w. ANDREWS.

ROY S. PETERSEN.

CERTIFICATE OF CORRECTION Patent No. 2,051,462, August 18, 1936.

CHARLES W. ANDREWS, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 14-, for the word "condenser" read condensate; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of October, A. D. 1936.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

